Understanding Statistics

The null hypothesis says the true difference equals what numerical value

0.05 or less

For a Pearson r of 0.60, what is the value of the coefficient of determination

0.36

when a researcher uses the 0.01 level, what are the odds of making a type 1 error

1 in 100

Name two circumstances under which median > mean for research

1. Ordinal data 2.

Do the following means on a performance test indicate an interaction between type of reward and age? Do the means indicate a main effect for type of reward?

1. Yes 2. No they are the same

What % of the participants lie w/in 1 SD unit of the mean in normal distribution

68%

When consumers of research incoperate proportions, what is a good idea?

Convert into a %

Which branch of statistics (inferential or descriptive) helps researchers to summarize data they can be easily comprehended?

Descriptive

Are % or proportions easier to comprehend?

%

When the relationship between two variables is perfect and inverse, what is the value of r

-1

if individuals in a group have all the same score, what is the SD?

0

what is the base for a proporiton

1

Percentages for different gruops are expressed on a common scale w/ what base

100

If there are means for four gruops (A B C D) there are how many indivdual pairs of means to be compared w/ a multiple comparison test?

4

A Pearson r of 0.70 is what percentage better than a Pearson r of 0

49%

This topic describes how many types of consideration for determing practical significance

5

if p=0.5 for a chi squre test, how many chances in 100 that the null hypothesis is true

5

interquartile range is the range of of what?

50% of the participants using, range between quarters

Do researchers use "univaritate" or Bivariate" to examine relationships between two nominal variables

Bivariate

Which type of analysis classifies participants in terms of two variables in order to examin the relationship between 2 variables

Bivariate Analysis

Are null hypothesis more likely to be explicityly stated in a "journal article' or "dissertation"

Dissertation

according to this topic, ethical considerations should play no role in the interpretation of the results of a study. Is this statement True or false

False

Suppose a researcher reported that for Group X, the median = 55.1 IQR=30, while for group Y median= 62.9, IQR=25. Which group has higher average score? Which group is more variable?

Group X

Which statistics discussed in this topic are measures of variablity

IQR

If a researcher tests a random sample instead of all members, is it likely the sample will be the same as the result the researchers would have obtained by testing the population?

In all likelihood no

Which branch of statistics helps researchers to draw inferences about the effects of sampling errors on their results?

Inferential statistics

Objective, multiple choiced achievement tests are usually assumed to measure at what level

Interval

The number of minutes of overtime work that employees perform is an exmaple of which scaled measurement

Intervals

What do researchers do if the proability is greater than 0.05

It remains on the possible list of explanations why the observed change occurred

Why is random sampling desirable even though it creates errors?

Less bias

What must be done in order to convert a coefficient of determination to a percentage

Must Square "r" to get a value and that can be turned into a percentage

if a distribution is skewed to the left, does it have a positive or negative skew?

Negative

Should determining the practical signifcance of a study's results be be a mechanical process

No

Does a crucial difference need to be numerically large to be of practical significance?

No (e.g. school's student scores crossing a funding threshold)

If a distribution has some extreme scores on the right (but not on the left) it is said to have what type of skew

Positive skew

what does the null hypothesis say about the difference between two sample means

There is no difference

What is the name of the error researchers make when they reject the null hypothesis when in fact it is a correct hypothesis

Type I Error

What is the name of an error researchers make if they fail to reject the full hypothesis when in fact it is an incorrect hypothesis

Type II Error

According to this topic, should client acceptability of a tx e considered when determining practical significance

Yes

If an ANOVA yields p<.05, should the null hypothesis be rejected

Yes

If the cost is very low, might a very small statistically significant difference be of practical significance?

Yes

Is it possible for a small difference to be statitcally significant

Yes

When reporting a percentage, is it a good idea to also report the underlying number of cases

Yes

if a researcher compares two means for significance, wil ANOVA and the t test yield the same probability

Yes, same value of p

What is meant by the term variability

amount by which participants vary or differ from eachother

ANOVA stands for what?

analysis of variance

What is the name of the test of the null hypothesis used in this topic?

chi-square

What is descriptive statistics?

describing the results actually were

is a relationship direct or inverse when those with high scores on one variable have high scores on the other ...visa versa?

direct

inferential statistics

numerical methods used to determine whether research data support a hypothesis or whether results were due to chance

When researchers study a sample, are the results called the "true" or "observed" results?

observed results

what is the symbol for probability

p

Is a researcher found that a chi-square test of a difference yielded a p < 0.05, what should they do?

reject null hypothesis

formal definition of the mean

the value around which the deviations sums to 0

Do researchers reject the null hypothesis when the probability of its truth is "high" or low

Low

which average is defined as the middle score

Median

Which average is defined as the most frequently occuring score?

Mode

if a researcher has four means on an achievement test for samples of students in four states, can he or she determine whether the set of differences, overall is statistically sig by using a t-test? explain. Could a researcher use a ANOVA for the same purpose?

No, t-test can only do two variables. Should be ANOVA

IF a researcher assigns a teacher to rank studenst according to their oral language skills, the researcher is using which scale of measurement

Ordinal

What is the name of the statistic that describes how many participants per 100 have a certain characteristic?

Percentage

Does a distribution w/ a tail to the right have a + or - skew

Positive

In most populations, income has what type of skew

Positive

IF an overall ANOVA for three or more means is significant, it can be followed by what type of test to determine the signifciance of the differences among the individual pairs of means?

Scheffe's test

By studyign samples , do researchers obtain statistics or parameters

Statistics

r=1.00 indicates ...

Strong correlation between the two quantities, one effects the other perfectly

What is an alternative way of saying a researcher has rejected the null hypothesis

The difference is statstically significant at the 0.05 level

Is it possible for two groups to have same mean but different standardizations?

yes

Should median be used for highly skewed distribution

yes

Which average is defined as the balance point in distribution

mean

Which average is usually reported when SD is reported

mean

synonym for averages

mean

should mean or medium be used with ordinal data

median

Which two statistics mentioned in this topic (median and IQR) are averages (i.e. measures of central tendency?

median and IQR

which one of the three averages is very seldom used in formal reports of research

mode

When a researcher uses a large sample, is he more or less liely to reject the null hypothesis

more likely

when the size of the difference between mean is large, is a researcher more or less likely to reject the null hypothesis that when the difference is small

more likely

If a researcher has a statistically sig result, should the null hypothesis remain on the list of viable explanations for an observed differnece

no

If an ANOVA yields p>.05, is/are the differences statistically significant?

no

Should mean be used for highly skewed distribution

no

Does the term "sampling error" refer to random errors or bias

random errors

What scale of measurement has an absolute zero

ratio

suppose a researcher drew random samples of urban, surburban and rural children , tested them for creativity, and obtained three means. Should the researcher do a one or two way ANOVA to test for significance? Why

One way, there is only one variable (location)

Weight measured in pounds is an example of which scale of measurement

Ratio Scale

What two scales of measurement have equal distances among the scores they yeild?

Ratio and interval

What decision should be made about the null hypothesis if a chi-squre test leads to conclusion that observed differences are unlikely to be due to random error

Reject

Significance tests are designed to determine the probabilities regarding the truth of what hypothesis?

The null hypothesis has been rejected or true

What does the null hypothesis say about sampling error?

The observed difference was due to the sampling error

Are significance tests associated w/ descriptive or inferential statistics

inferential

Is margin of error a "descriptive" or an "inferential" statistic

inferential

is range or interquartile range a more reliable statistic

interquartile range

In an ANOVA table, which statistic is of greatest interest to the typical consumer of research?

p value

what should p be to declare a difference statistically significant

p<0.05

Do the following means on an achievement test indicate an interaction between the method of instruction (A vs B) and the aptitude of the students (high vs low) Do the means indicate a main effect for method of instruction? Do the means indicate a main effect for Aptitude?

1. No b/c the method of insturction. 2. Yes 3. No

The middle 68% of the participants in normal distribution have scores between what two values if mean=100, SD 15

85, 115

Describe a hypothetical study in which it would be appropriate to conduct a chi-squre test for univariate data

Living in Idaho and people would fill in Nominal results

According to this topic, should the typical consumer try to interpret the value of df?

No

Are the values of t and df of any special interest to typical consumers of research?

No

If you fail to reject a null hypothesis, is the difference in question statistically significant

No

Should typical consumers of research be conerned w/ the values of the degrees of freedom?

No

t=2, df=20, p>.05 for the difference of the two means. Should the null hypothesis be rejected?

No

If a researcher asks participants to name the country they are born in, what scale of measurement are they using

Nominal

Which scale of measurement is at the lowest level

Nominal

What is the name of the curve that is symmetrical

Normal curve

By studing populations, do researchers obtain "statistics" or parameters"

Parameters

Pearson "r" stands for

a relationship between two quanitative sets of scores they compute a correlation coefficient. The coefficent is r